The present invention generally relates to a video signal processor.
Conventional video signal processors have separately a noise reduction (hereinafter referred to as NR) circuit for a baseband video signal supplied by reproducing a video tape and a luminance/chrominance separation (hereinafter referred to as Y/C separation) processing circuit.
Referring now to FIGS. 1 and 2, a conventional video signal processor will be briefly described.
FIG. 1 shows a conventional NR processing circuit adapted for processing such baseband video signals. While, FIG. 2 shows a conventional inter-frame non-correlation component removing circuit for performing a motion-adaptive Y/C separation for such composite video signals.
A baseband video signal reproduced by VTRs, laser disc players and the like is supplied to an input terminal 101. The baseband video signal is supplied to an A/D converter 103. The A/D converter 103 converts the input video signal in an analog format into a corresponding digital format signal. Then following video signal processing will be carried out in digital manner. Thus if the following video signal processing is carried out in a analog manner, the A/D converter 103 will be deleted. The video signal in this stage will be referred to as a 0H video signal hereinafter for distinguishing from other video signals as described later.
The 0H video signal is supplied to a first line memory 105. The first line memory 105 delays the 0H video signal by one line period. The delayed video signal will be referred to as a 1H video signal hereinafter. The 1H video signal is supplied to a second line memory 107.
The second line memory 107 delays the 1H video signal by additional one line period. The delayed video signal from the second line memory 107 will be referred to as a 2H video signal hereinafter.
The 0H video signal, the 1H video signal and the 2H video signal are processed by band-pass filters (BPFS) 109, 111 and 113 for extracting a prescribed frequency band with a center frequency of a 7.16 MHz, respectively.
The 0H video signal, the 1H video signal and the 2H video signal each having the prescribed frequency band are supplied to a common inter-line non-correlation component extractor 115 for extracting a non-correlation component among the three video signals. The extracted inter-line non-correlation components are then supplied to a gain adjuster 117.
The gain adjuster 117 adjusts the gain of the inter-line non-correlation component.
The output of the gain adjuster 117 can be assumed as a noise component. The output of the gain adjuster 117 is thus subtracted from the 1H video signal at the subtractor 119 for obtaining an NR processed signal. The NR processed video signal is output through an output terminal 121.
In the conventional inter-frame non-correlation control circuit as, as shown in FIG. 2, a composite video signal in a form of an NTSC system recorded video signal is input to an input terminal 201. The composite video signal is then supplied to an A/D converter 203. The A/D converter 203 converts the input video signal in an analog format into a corresponding digital format signal. The video signal in this stage will be referred to as a 0H video signal hereinafter for distinguishing from other video signals as described later.
The 0H video signal is supplied to a first line memory 205. The first line memory 205 delays the 0H video signal by one line period. The delayed video signal will be referred to as a 1H video signal hereinafter. The 1H video signal is supplied to a second line memory 207.
The second line memory 207 delays the 1H video signal by additional one line period. The delayed video signal from the second line memory 207 will be referred to as a 2H video signal hereinafter.
The 0H video signal, the 1H video signal and the 2H video signal are processed by band-pass filters (BPFS) 209, 211 and 213 for extracting a prescribed frequency band with a center frequency of a 3.58 MHz or a color sub-carrier frequency, respectively.
The 0H video signal, the 1H video signal and the 2H video signal each having the prescribed frequency band are supplied to a common inter-line non-correlation component extractor 215 for extracting a non-correlation component among the three video signals. The extracted inter-line non-correlation components are then supplied to an adder 228 through the non-linear filter 227, and wherein the inter-line non-correlation components are added with three-dimensional chrominance components C3 as described later. Then the added signal is supplied to a subtractor 219.
The subtractor 219 subtracts the output signal of the non-linear filter 217 from the 1H video signal. Thus a two-dimensional luminance signal Y2 is obtained from the subtractor 219 and then supplied to one input terminal of a mixer 223.
The 1H video signal is also supplied to an inter-frame non-correlation signal remover 225 wherein the inter-frame Y/C separation is performed on the 1H video signal. A three-dimensional luminance signal Y3 is thus obtained from the inter-frame non-correlation signal remover 225 and supplied to another input terminal of the mixer 223. While a three-dimensional chrominance signal C3 obtained from the inter-frame non-correlation signal remover 225 is supplied to another input terminal of the adder 228, and wherein the three-dimensional chrominance signal C3 is added with the above-mentioned inter-line non-correlation components.
The mixer 223 mixes the two-dimensional luminance signal Y2 from the subtractor 219 and the three-dimensional luminance signal Y3 from the inter-frame non-correlation component remover 225 in the ratio defined by a motion signal which is obtained separately as described later. A mixed luminance signal Y is output through an output terminal 227.
Such a conventional NR circuit, as shown in FIG. 1, and such a conventional Y/C separation circuit, as shown in FIG. 2, are individually dedicated for a sole use of the NR and the Y/C separation. Thus VTRs must incorporate independent units of such an NR circuit and a Y/C separation circuit.
As a result, conventional VTRs experience an increase of circuit scale, thus causing also increases of costs.
Here, the Japanese Patent Application Tokkai-Hei 4-347991 discloses a inter-frame non-correlation removing (or extracting) circuit, or a video signal processing circuit for separating a luminance signal from a composite video signal.
However, in the conventional inter-frame non-correlation removing (or extracting) circuit disclosed in the Japanese Patent Application it is required that LPFs in a luminance signal extraction system and BPFs in a chrominance signal extraction system are constructed in a complementary relationship with each other for preserving a flat frequency characteristics. However such a requirement has a drawbacks that it not only restricts design conditions, but also causes the increases of circuit scale and costs of apparatus.
Further, in the conventional inter-frame non-correlation removing (or extracting) circuit disclosed in the Japanese Patent Application comb-filters for separating luminance signals is constructed in a non-cyclic type. Thus there is a drawback that it cannot achieve a sufficient S/N ratio.
It is, therefore, an object of the present invention is to provide a video signal processor which is not only reduced in the circuit scale but also improved in precision of NR operation, by constructing a single unit which is operable in common for the NR operation and the Y/C separation.
It is another object of the present invention to provide a video signal processor which is able to not only extract a luminance signal with a flat horizontal frequency characteristics by a simple circuit configuration, but also improve the S/N ratio in a luminance signal low band component, in particular, a video signal processor which is able to extract an inter-frame non-correlation component.
In order to achieve the above object, a video signal processor according to a first aspect of the present invention includes an input receiving unit for selectively receiving either of a baseband video signal and a composite video signal are selectively input as an input video signal thereto, a 1H delay unit for delaying the selected input video signal by one line period (1H), an inter-line non-correlation component extractor for extracting inter-line non-correlation components between the input video signal and the 1H delay signal from the 1H delay unit, an inter-frame non-correlation component remover for removing inter-frame non-correlation components from the selected input video signal, a first subtractor responsive to the selection of the baseband video signal for subtracting the inter-line non-correlation component from the baseband video signal processed the inter-frame non-correlation component removal at the inter-frame non-correlation component remover to result noise-reduced baseband video signals, a second subtractor responsive to the selection of the composite video signal the inter-line non-correlation component from the input composite video signal to result a first luminance signal, and a mixer for mixing a second luminance signal resulted from the inter-frame non-correlation component removal at the inter-frame non-correlation component remover with the first luminance signal from the second subtractor at a ratio defined by a motion signal to result a motion-adaptively processed luminance signal.
In order to achieve the above object, a video signal processor according to a second aspect of the present invention includes an input receiving unit for selectively receiving either of a baseband video signal and a composite video signal are selectively input as an input video signal thereto, a 1H delay unit for delaying the selected input video signal by one line period (1H), a 2H delay unit for delaying the selected input video signal by two line periods (2H), a three-dimension inter-line non-correlation component extractor for extracting three-dimension inter-line non-correlation components among the input video signal, the 1H delay signal from the 1H delay unit and the 2H delay signal from the 2H delay unit, an inter-frame non-correlation component remover for removing inter-frame non-correlation components from the selected input video signal, a first subtractor responsive to the selection of the baseband video signal for subtracting the three-dimension inter-line non-correlation component from the baseband video signal processed the inter-frame non-correlation component removal at the inter-frame non-correlation component remover to result noise-reduced baseband video signals, a second subtractor responsive to the selection of the composite video signal the three-dimension inter-line non-correlation component from the input composite video signal to result a first luminance signal, and a mixer for mixing a second luminance signal resulted from the inter-frame non-correlation component removal at the inter-frame non-correlation component remover with the first luminance signal from the second subtractor at a ratio defined by a motion signal to result a motion-adaptively processed luminance signal.
In order to achieve the above object, a video signal processor according to a third aspect of the present invention includes an input receiving unit for selectively receiving either of a baseband video signal and a composite video signal are selectively input as an input video signal thereto, a first BPF for extracting a prescribed frequency band from the selected input video signal, a 1H delay unit for delaying the selected input video signal by one line period (1H), a second BPF for extracting the prescribed frequency band from the 1H delay signal, an inter-line non-correlation component extractor for extracting inter-line non-correlation components between the input video signal from the first BPF and the 1H delay signal from the second BPF, each having the prescribed frequency band, an inter-frame non-correlation component remover for removing inter-frame non-correlation components from the selected input video signal, a first subtractor responsive to the selection of the baseband video signal for subtracting the inter-line non-correlation component from the baseband video signal processed the inter-frame non-correlation component removal at the inter-frame non-correlation component remover to result noise-reduced baseband video signals, a second subtractor responsive to the selection of the composite video signal the inter-line non-correlation component from the input composite video signal to result a first luminance signal, and a mixer for mixing a second luminance signal resulted from the inter-frame non-correlation component removal at the inter-frame non-correlation component remover with the first luminance signal from the second subtractor at a ratio defined by a motion signal to result a motion-adaptively processed luminance signal.
In order to achieve the above object, a video signal processor for processing a luminance/chrominance (Y/C) separation for a composite video signal according to a fourth aspect of the present invention includes a first comb filter for extracting luminance signal inter-frame non-correlation components from a composite video signal, a second comb filter for extracting chrominance signal from the composite video signal, and a subtractor for subtracting the luminance signal inter-frame non-correlation components from the first comb filter and the chrominance signal from the second comb filter from the composite video signal to result a luminance signal.